The effects of 53 hours of sleep deprivation on moral judgment.

STUDY OBJECTIVES: Functional neuroimaging studies suggest a prominent role for the medial prefrontal cortex in the formation of moral judgments. Activity in this region has also been shown to decline significantly during sleep loss. We therefore examined the effects of 2 nights of sleep deprivation on several aspects of moral judgment. DESIGN: Participants made judgments about the "appropriateness" of various courses of action in response to 3 types of moral dilemmas at rested baseline and again following 53 hours of continuous wakefulness. SETTING: In-residence sleep laboratory at the Walter Reed Army Institute of Research. PARTICIPANTS: Twenty-six healthy adults (21 men, 5 women). INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Compared to baseline, sleep deprivation resulted in significantly longer response latencies (suggesting greater difficulty deciding upon a course of action) only for Moral Personal (i.e., emotionally evocative) dilemmas, whereas response times to Moral Impersonal (less emotionally evocative) and Non Moral dilemmas did not change significantly with sleep loss. The effect of sleep deprivation on the willingness to agree with solutions that violate personally held moral beliefs was moderated by the level of emotional intelligence, as measured by the Bar-On EQ-i. Persons high in emotional intelligence were less susceptible to changes in moral judgments as a function of sleep loss. CONCLUSIONS: These findings suggest that sleep deprivation impairs the ability to integrate emotion and cognition to guide moral judgments, although susceptibility to the effects of sleep loss on this ability is moderated by the level of emotional intelligence.

Interspecific scaling of the morphology and posture of the limbs during the locomotion of cats (Felidae).

For phylogenetically diverse mammals, ranging from small rodents to large ungulates, the generalization that limb erectness increases with increased size is supported by some size-dependent scaling relationships of appendicular skeletal anatomy as well as a limited number of direct observations of limb posture during locomotion. If size alone is the causal basis for different limb posture, then the erectness of limbs should increase significantly with increased size within a phylogenetically narrow lineage, but such data are sparse. Thus, to better establish the correlation between size and posture of mammalian limbs, we quantified the scaling relationships between mass and limb dimensions and kinematics during walking of nine species within the felid (cat) clade, which has qualitatively similar limb design. We studied the domestic cat, serval, ocelot, lynx, leopard, cheetah, cougar, lion and tiger, which had masses ranging from <4 kg to nearly 200 kg. Apart from variation associated with overall size, the lengths of the appendicular skeletal structures of most of the felid species were morphologically very similar in multivariate space. The kinematics of the limbs were also relatively uniform, and size had little predictive value for limb posture among felid species. Only three out of a total of 24 angular variables at footfall and midstance changed significantly (0.02